104 The American Naturalist. [February, 
Mr. Elliott thinks “ that it will be nearly correct to assign to each 
male from twelve to fifteen females, occupying the stations nearest 
the water, and those back in the rear from five to nine. I have 
counted forty-five cows all under one bull.’” 
2nd, The no less astonishing disparity in size between the 
sexes. The average length of the male is 7 14 feet, while that of 
the female is 4 feet.. The male weighs 450 lbs., while the female 
weighs only 85 lbs. It will thus be seen that the male weighs 
nearly six “mes as much as the female. 
Two questions arise in view of the above facts: 
Ist, Is there any relation between polygamy and sexual dis- 
parity in size? 2nd, If so, what is that relation? 
The Pinnipedia are fortunately sufficiently numerous in species 
and individuals to furnish an ample field for the study of both of 
the above questions. They are all eminently gregarious in habit, 
a condition favorable to polygamy. The order furnishes ex- 
amples of both monogamous andpolygamous species, and almost 
every degree of sexual disparity in size to be found in the Mam- 
malia. We can easily construct a series of species, ascending from 
those exhibiting the least sexual disparity to those exhibiting the 
greatest. We can then see what, if any, relation exists between 
sexual disparity and polygamy. We shall presently see that pug- 
nacity on the part of the males plays a not unimportant rôle. in 
our discussion, and for that reason the fighting proclivities of the 
males will also be noted. 
The following arrangement, then, illustrates what might be 
termed the ascending series of sexual disparity. The relation of 
the sexes (monogamy, promiscuity, or polygamy) and the relative 
pugnacity of the males in relation to other males of the same 
species will also be noted in each case. 
Odobenus rosmarus (Walrus). 
(2) Sexes nearly equal in size, the female not being notably 
smaller than the male. (2) Monogamous, according to the only 
? Quoted from “ Monograph of North American Pinnipeds” (Allen). Nearly all 
Material used in the above article has been taken from that work. 
